We used nuclear hyperfine spectroscopies and a 57Fe probe layer approach to study the depth-dependent magnetic properties of ultrathin Fe films on NiO(0 0 1), a system exhibiting exchange bias. Conversion electron Mössbauer spectroscopy and nuclear resonance scattering of synchrotron radiation were employed. The samples were two Fe films with a thickness (8–10 ML) slightly above the critical thickness for the onset of ferromagnetism at room temperature, in which a 2 ML-thick probe layer, enriched in the 57Fe Mössbauer isotope, was embedded at different depths from the Fe/NiO interface. Both techniques indicate that inside the film Fe has a metallic character, while at the interface with NiO different Fe phases are present. The main conclusion is that already a few monolayers from the interface with NiO the magnetic properties of Fe are bulk-like.
1 Feb 2010
Volume: 268 Issue: 3-4 Pages: 361-364
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms